Safety regulations require that certain safety-related devices and systems be monitored to help ensure proper operation of the safety-related items. One source of errors for such equipment includes transients such as radiation-induced soft errors (SERs). SERs can occur at any time and may adversely affect the operation of a processor that is performing safely-related processing. Other sources of errors include permanent (e.g., Direct Current) errors and timing—(e.g., Alternating Current) based faults in logic.
Redundant logic is often used to verify the operation of the processor that is performing safely-related processing. However, using redundant logic to continuously generate comparison results that are used to verify proper operation of the processor is often relatively expensive because of the additional complexity required by the redundant logic and additional input/output (I/O) ports required. Additionally, there is additional concern for common-cause failures when redundant logic is used because failures are often not detected when the redundant logic responds to the common cause in the same manner. Thus, the approach of using and comparing the results of redundant logic would entail additional costs for verification of devices or systems that are performing safely-related functions and processes.